Color picture tube with mounting means for electrostatic beam convergence plates

ABSTRACT

In a color picture tube of the single-gun, plural-beam type in which all of the beams pass through the center of an electron lens for focusing the beams on the color phosphor screen with two of the beams emerging from the lens along paths divergent from the optical axis of the lens, and pairs of convergence deflecting plates are arranged along the divergent paths and have voltages applied thereacross to produce electric fields by which the divergent beams are deflected for converging all of the beams at a common point on the aperture grill associated with the screen; the outer plate of each pair of convergence deflecting plates is mounted with respect to the corresponding inner plate by means of conductive members extending outwardly from the latter past the sides of the outer plate to glass or insulating members extending across the outer surface of the outer plate, and hence disposed outside the electric field, and the ends of the outer plate are preferably bent outwardly to shield the electric field from the effect of the potential of the adjacent insulating members.

United States Patent Inventor Senri Miyaoka Kanagawa-ken, Japan Appl. No. 815,051 Filed Apr. 10, 1969 Patented Mar. 23, 1971 Assignee Sony Corporation Tokyo, Japan Priority Apr. 14, 1968 Japan 43124593 COLOR PICTURE TUBE WITH MOUNTING MEANS FOR ELECTROSTATIC BEAM CONVERGENCE PLATES 2 Claims, 5 Drawing Figs.

Primary Examiner-Robert Segal Attorneys-Albert C. Johnston, Robert E. Isner, Lewis H.

Eslinger and Alvin Sinderbrand ABSTRACT: In a color picture tube of the single-gun, pluralbeam type in which all of the beams pass through the center of an electron lens for focusing the beams on the color phosphor screen with two of the beams emerging from the lens along paths divergent from the optical axis of the lens, and pairs of convergence deflecting plates are arranged along the divergent paths and have voltages applied thereacross to produce electric fields by which the divergent beams are deflected for converging all of the beams at a common point on the aperture grill associated with the screen; the outer plate of each pair of convergence deflecting plates is mounted with respect to the corresponding inner plate by means of conductive members extending outwardly from the latter past the sides of the outer plate to glass or insulating members extending across the outer surface of the outer plate, and hence disposed outside the electric field, and the ends of the outer plate are preferably bent outwardly to shield the electric field from the effect of the potential of the adjacent insulating members.

QGLGh PKC'I'URE TUBE WITH MGUNTING MEANS FOR ELEQWGS'EATIC BEAM CONVERGENCE PLATES This invention relates generally to color picture tubes of the single-gun, plural-beam type, and particularly to tubes of that type in which the plural beams are passed through the optical center of a common electron lens by which the beams are focused on the color phosphor screen.

In single-gun, plural-beam color picture tubes of the described type, for example, as specifically disclosed in the copending US. application Ser. No. 697,414, filed Jan. 12, 1963 and having a common assignee herewith, three laterally spaced electron beams are emitted by a beam-generating or cathode assembly and directed in a common substantially horizontal plane with the central beam coinciding with the optical axis of the single electron focusing lens and the two outer beams being converged to cross the central beam at the optical center of the lens and thus emerge from the latter along paths that are divergent from the optical axis. Arranged along such divergent paths are respective pairs of convergencedeflecting plates having voltages applied thereacross to produce electric fields which laterally deflect the divergent beams in a substantially horizontal plane for causing all beams to converge at a point on the apertured beam-selecting grill or shadow mask associated with the color screen.

In a tube of the described type, it is desirable that the convergence-deflecting plates be assembled together with the other components of the single-gun structure for mounting, as a unit, within the neck portion of the tube envelope. Further, it is necessary that the convergence-deflecting plates, between which an electric field is established for deflecting the divergent beam passing therethrough, be insulated from each other. In practice, the inner plates may be mounted at one end on an electrode of the electron focusing lens so as to extend therefrom in spaced relation to each other for passage of the central beam therebetween, while the outer plates are mounted on the inner plates in outwardly spaced relation to the latter by means of insulating members extending therebetween. However, in that case the insulating members are located in the electric fields established between the inner and outer plates and the potentials of the insulating members disturb the fields and may cause misconvergence of the beams.

Accordingly, it is an object of this invention to provide simple means for mounting the convergence-deflecting plates without disturbing the uniformity of the electric fields therebetween.

In accordance with an aspect of the invention, the outer plate of each pair of convergence-deflecting plates is mounted with respect to the inner plate of each pair by means of conductive members, such as pins, extending outwardly from the inner plate past the opposite sides of the outer plate and being connected to glass or other insulating members which extend across the outer surface of the outer plate so as to be remote from the electric field established between the pair of plates.

It is a further feature of the invention to provide each outer plate with outwardly bent end portions so that the electric field between the pair of convergence-deflecting plates will be shielded from the effect of the potential of the insulating members even when the latter are located adjacent the end portions of the outer plate.

The above, and other objects, features and advantages of the invention, will be apparent in the following detailed description of an illustrative embodiment which is to be read in connection with the accompanying drawings, wherein:

HO. 1 is a schematic sectional view in a horizontal plane passing through the axis of a single-gun, plural-beam color picture tube of the type to which this invention may be applied;

FIG. 2 is a sectional view similar to that of FIG. 1, but showing the structural details of such tube having its convergencedeilecting plates mounted in accordance with an embodiment of this invention;

FIG 3 is an enlarged, fragmentary sectional view showing the mounting of the convergence-deflecting plates;

FIG. 4 is a side elevational view of the structure appearing on FIG. 3; and

FIG. 5 is a transverse sectional view taken along the line V-V on FIG. 4.

Referring to the drawings in detail, and initially to FIG. l thereof, it will be seen that a single-gun, plural-beam color picture tube of the type to which this invention may be applied comprises a glass envelope (indicated in broken lines) having a neck N and cone C extending from the neck to a color screen S provided with the usual arrays of color phosphors S S and S and with an apertured beam selecting grill or shadow mask G Disposed within neck N is an electron gun A having cathodes K K and K each of which is constituted by a beam-generating source with the respective beamgenerating surfaces thereof disposed as shown in a plane which is substantially perpendicular to the axis of the electron gun A. In the embodiment shown, the beam-generating surfaces are arranged in a straight line so that the respective beams B 8 and B emitted therefrom are directed in a substantially horizontal plane containing the axis of the gun, with the central beam B being coincident with such axis. A first grid G, is spaced from the beam-generating surfaces of cathodes K K and K and has apertures g g and 3,, formed therein in alignment with the respective cathode beam-generating surfaces. A common grid G, is spaced from the first grid G, and has apertures g 3, and formed therein in alignment with the respective apertures of the first grid 6,. Successively arranged in the axial direction away from the common grid G are open-ended, tubular grids or electrodes G,,, G,, and G,, respectively, with cathodes K K and K grids G, and G,, and electrodes 6,, G,, and G, being suitably maintained in the depicted, assembled positions thereof.

For operation of the electron gun A of FIG. 1, appropriate voltages are applied to the grids G, and G and to the electrodes G,,, G,, and G,,. Thus, for example, a voltage of 0 to minus 400v. is applied to the grid G,, a voltage of 0 to 500v. is applied to the grid G,, a voltage of 13 to 20kv. is applied to the electrodes 6, and G and a voltage of 0 to 400v. is applied to the electrode G,,, with all of these voltages being based upon the cathode voltage as a reference. As a result, the voltage distributions between the respective electrodes and cathodes, and the respective lengths and diameters thereof, may be substantially identical with those of a unipotential single-beamtype electron gun which is constituted by a single cathode and first and second, single-apertured grids.

With the applied voltage distribution as described hereinabove, an electron lens field will be established between grid G and the electrode G,, to form an auxiliary lens L as indicated in dashed lines, and an electron lens field will be established around the axis of electrode G,, by the electrodes G G and G,,, to form a main lens L, again as indicated in dashed lines. In a typical use of electron gun A bias voltages of l00v., 0v., 300v., 20kv., 200v. and 20v. may be applied respectively to the cathodes K K and K the first and second grids G, and G and the electrodes G,,, G, and G,,.

Further included in the electron gun A of FIG. 1 are electron beam convergence-deflecting means F which comprise inner shielding plates P and P disposed in the depicted spaced, relationship at opposite sides of the gun axis, and axially extending, deflector plates 0 and O which are disposed, as shown, in outwardly spaced, opposed relationship to shielding plates P and P, respectively. Although depicted as substantially straight, it is to be understood that the deflector plates Q and Q may, alternatively, be somewhat curved or outwardly bowed, as is well known in the art.

The shielding plates P and P are equally charged and disposed so that the central electron beam B will pass substantially undeflected therebetween, while the deflector plates 0 and Q have negative charges with respect to the plates P and P so that electron beams B and E will be convergently a voltage V which is equal to the voltage applied to the electrode G may be applied to both shielding plates P and P, and a voltage V which is some 200 to 300v. lower than the voltage V is applied to the plates and Q to result in the plates P and P being at the same potential, and in the application of a deflecting voltage difference or convergence-deflecting voltages V between the plates P and Q and the plates P and Q and it is, of course, this convergence-deflecting voltage V which will impart the requisite convergent deflection to the electron beams 13,, and B in operation, the electron beams B B and 8;, which emanate from the beam-generating surfaces of the cathodes K K and K will pass through the respective grid apertures g g and g to be intensity modulated with what may be termed the red," green and blue" intensity modulation signals applied between the said cathodes and the first grid (3,. The electron beams will then pass through the common auxiliary lens L to cross each other at the center of the main lens L. Thereafter, the central electron beam B will pass substantially undeflected between shielding plates P and P since the latter are at the same potential. Passage of the electron beam 3,, between the plates P and Q and of the electron beam B between the plates P and Q will, however, result in the convergent deflections thereof as a result of the convergence-deflecting voltage V applied therebetween, and the system of FIG. 1 is so arranged that the electron beams B B and 3,, will desirably converge or cross each other at a common spot centered in an aperture of the beam-selecting grill or mask G so as to diverge therefrom to strike the respective color phosphors of a corresponding array thereof on screen S. More specifically, it may be noted that the color phosphor screen S is composed of a large plurality of sets or arrays of vertically extending red," green and blue" phosphor stripes or dots S S and 8,, with each of the arrays or sets of color phosphors forming a color picture element. Thus, it will be understood that the common spot of beam convergence corresponds to one of the thusly formed color picture elements.

The voltage V may also be applied to the lens electrodes G and G and to the screen S as an anode voltage as well as to the aperture grill G Electron beam scanning of the face of the color phosphor screen is effected in conventional manner, for example, by horizontal and vertical deflection yoke means indicated in broken lines at D and which receives horizontal and vertical sweep signals whereby a color picture will be provided on the color screen. Since, with this arrangement, the respective electron beams are each passed, for focusing, through the center of the main lens L of the electron gun A, the beam spots formed by impingement of the beams on the color phosphor screen S will be substantially free from the effects of coma and/or astigmatism of the said main lens, whereby improved color picture resolution will be provided.

Referring now to FIG. 2, it will be seen that, in a structural embodiment of a color picture tube of the type shown schematically on FIG. 1, the first and second grids G, and G and the electrodes 6;, G and G are assembled together and maintained in the relative positions shown by means of longitudinally extending insulating beads 22 arranged at circumferentially spaced locations around the gun structure and being connected to the several parts by radial pins anchored in the beads. The gun structure is positioned within neck portion N of the tube envelope by slidable engagement of beads 22 with the inner surface of neck portion N and further by the engagement with such inner surface of the peripheries of axially spaced support rings 30, 31 fixed to an extension of electrode Conductive pins 21 extend through the end wall of neck portion N, and conductive leads 2! connect such pins to control grid 6,, common grid G and the electrode G, for the provision of suitable operating voltages thereto. Further, a conductor 19 connects electrodes 6;, and G so as to have the same potential applied thereto. Spring contact elements 27 extend from a flange 53 at the forward end of the extension of electrode (3 and engage a conductive layer 28 which is applied to the interior surface of cone portion C and extends into the adjacent part of neck portion N of the tube envelope. The anode voltage V is applied to layer 28 by way of an anode button (not shown) in cone portion C, and thus is applied through contact elements 27 to electrode 0 and through con ductor 19 to electrode G a As shown particularly on FIGS. 3 and d, the inner convergence-deflecting plates P and P have laterally spaced tabs 23 and 23 extending at right angles thereto at the ends of such plates adjacent to electrode 0,, and such tabs 23 and 23' are welded or otherwise secured to flange 53 so as to support plates P and P from electrode 6;, in the spaced relation required for the passage of beam B therebetween. Further, by way of tabs 23, 23', voltage V is applied to plates P and P from electrode G The voltage V for application to the outer convergence-deflecting plates 0 and Q is applied to a button 39 in neck portion N, which button has a shoe 38 at the inside of neck portion N engaged by a conductor 36 extending through an insulator 35 and connected to plate 0. Further, a conductive lead 40 extends from plate Q to plate 0' for applying the voltage V to the latter.

In accordance with this invention, the outer convergencedeflecting plates 0 and Q are mounted in outwardly spaced relation to the plates P and P, respectively, by means of conductive pins 24 and 24 extending outwardly from side portions of plates P and P, respectively, and passing, without contact, through notches or cutouts 51 and 51 (FIGS. 4 and 5) provided in the side edges of plates 0 and Q. The outer ends of pins 24 and 24 are anchored in glass or other insulating members 25 and 25 which extend across, and are secured to the outer surfaces of plates Q and Q, respectively, adjacent the opposite end portions of the latter. Further, as shown particularly on FIG. 3, the opposite end portions of plates Q and Q are preferably bent outwardly, that is, in the directions away from the plates P and P, respectively.

It will be apparent that, in the above arrangement according to this invention, the various parts of the convergence-deflecting device F are assembled together with the other components of the gun A to form a unit that is easily installed in its operative position within the neck portion N of the tube envelope. Further, in such arrangement, the mounting for the outer convergence-deflecting plates Q and Q is of a simple character which effectively insulates plates 0 and Q from the plates P and P and yet avoids the presence of insulating members in the spaces between plates P and Q and plates P and Q where the electric fields for convergence deflection of beams B and B are produced. Since the insulating members 25 and 25' are outside of such electric fields, they cannot disturb the uniformity of the fields and hence do not cause misconvergence of the beams. Further, the outwardly bent end portions of plates 0 and Q in accordance with this invention ensure that the electric fields will be isolated from any disturbing effect of the potentials of insulating members 25 and 25' even though the latter are mounted on plates 0 and Q adjacent the end portions of the latter for maximum stability of the positioning of plates Q and Q relative to plates P and P.

Having described an illustrative embodiment of the invention with reference to the drawings, it is to be understood that the invention is not limited to that precise embodiment, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention.

I claim:

1. In a color picture tube in which a plurality of electron beams are passed through the center of lens means by which the beams are all focused on a color screen with one of the beams emerging from said lens means along the axis of the latter and two other beams emerging from the lens means along paths divergent from said axis; electrostatic beamdetlecting means comprising pairs of convergence-deflecting plates arranged along said divergent paths at the inner and outer sides of the respective paths considered in relation to said axis of the lens means, the inner plates of said pairs being spaced apart and at the same potential for the undeflected passage of said one beam therebetween, a different potential being applied to the outer plates of said pairs so that an electric field is produced between each pair of plates for deflecting the respective beam passing therethrough in the direction to converge all of said beams at a common spot corresponding to a color picture element of said screen, insulating members extending across, and being secured to the outer surface of said outer plate of each pair so as to be outside of the corresponding electric field, and conductive support members extending outwardly from said inner plate of each of said pairs past the opposite sides of the respective outer plate and being secured 

1. In a color picture tube in which a plurality of electron beams are passed through the center of lens means by which the beams are all focused on a color screen with one of the beams emerging from said lens means along the axis of the latter and two other beams emerging from the lens means along paths divergent from said axis; electrostatic beam-deflecting means comprising pairs of convergence-deflecting plates arranged along said divergent paths at the inner and outer sides of the respective paths considered in relation to said axis of the lens means, the inner plates of said pairs being spaced apart and at tHe same potential for the undeflected passage of said one beam therebetween, a different potential being applied to the outer plates of said pairs so that an electric field is produced between each pair of plates for deflecting the respective beam passing therethrough in the direction to converge all of said beams at a common spot corresponding to a color picture element of said screen, insulating members extending across, and being secured to the outer surface of said outer plate of each pair so as to be outside of the corresponding electric field, and conductive support members extending outwardly from said inner plate of each of said pairs past the opposite sides of the respective outer plate and being secured to said insulating members on the latter, whereby to maintain said plates of each pair in fixed spaced relation to each other while avoiding disturbance of the respective field by the presence of insulators therein, the opposite end portions of said outer plate of each of said pairs being bent outwardly to shield the ends of the respective field from the influence of the potential of said insulating members.
 2. A color picture tube according to claim 1, in which said insulating members are located adjacent said outwardly bent end portions of the respective outer plates. 